"As I look at Baltimore, I see myself. I would not be standing in front of you today as CEO of Baltimore public schools if it were not for education. And I want to create the same opportunity for their children," Thornton said.

The announcement was made in Baltimore by Dr. Shanaysha M. Sands, Chair Baltimore City Board of School Commissioners, and Baltimore Mayor Stephanie Rawlings-Blake.

“We are extremely grateful to Dr. Thornton for his tireless efforts to improve outcomes for students in Milwaukee Public Schools,” said Milwaukee Board of School Directors President Dr. Michael Bonds. “MPS has made significant progress under Dr. Thornton’s leadership. He is one of the top superintendents in the nation and has done a phenomenal job. He will be missed.”

Thornton, 59, will replace Andres Alonso, who stepped down last year to assume a prestigious professorship at the Harvard Graduate School of Education.

"Dr. Thornton is the right person at the right time for City Schools," said Baltimore City Schools board chair Shanaysha Sauls. "We are thrilled to attract someone with his national profile in public education to Baltimore."

Details of Thornton’s transition to Baltimore City Public Schools are being developed.

Baltimore and Milwaukee are similar in size. Milwaukee has a little more than 78,000 students while Baltimore has 84,000. Their budgets are also about the same at a little more than $1 billion a piece.

Sauls said that Baltimore City Schools is working on long-term reforms in several areas where Thornton has "deep experience and demonstrated expertise."

Thornton signed a contract renewal with MPS just last summer.

Mayor Tom Barrett praised Thornton for turning around district finances but called the search for a new superintendent an opportunity for MPS.

"It has been painful, but they have addressed a lot of the fiscal issues. I think the big issues remain the academic issues. We want to see a significantly higher graduation rate. We want to see better performance," Barrett said.

Gov. Scott Walker meanwhile challenged MPS to use this as a time change its operation.

"My hope is that as part of this process, they'll not only be looking to find a new leader, they'll be looking to new ways to embrace the tools we've giving to plenty of other school districts across the state and use those in Milwaukee," Walker said

Before Milwaukee, Thornton was superintendent of the Chester Upland School District, in Chester, Pa. He was also chief academic officer in Philadelphia and he has held top school leadership jobs in Maryland and North Carolina.

MILWAUKEE IS LOSING ITS SCHOOL SUPERINTENDENT. DR. GREGORY THORNTON WAS INTRODUCED TODAY AS THE NEW HEAD OF THE BALTIMORE SCHOOL SYSTEM. IT'S A STORY WISN-12 NEWS FIRST BROKE YESTERDAY. TONIGHT, KENT WAINSCOTT LOOKS AT THE POTENTIAL FALLOUT FOR M-P-S AND ITS STUDENTS. IT WAS A WARM WELCOME AS DR. GREGORY THORNTON TALKED ABOUT HIS NEW ROLE LEADING BALTIMORE'S SCHOOLS. DR. GREGORY THORNTON - AS I LOOK AT BALTIMORE I SEE MYSELF. I WOULD NOT BE STANDING IN FRONT OF YOU TODAY AS CEO OF BALTIMORE PUBLIC SCHOOLS IF IT WERE NOT FOR EDUCATION. AND I WANT TO CREATE THE SAME OPPORTUNITY FOR THEIR CHILDREN. BUT AT THAT WAS HAPPENING, SCHOOL OFFICIALS IN MILWAUKEE HAD NOT STILL NOT OFFICIALLY HEARD THAT THORNTON WAS LEAVING. DR. MICHAEL BONDS - HE'S NOT HAD A CONVERSATION WITH YOU ABOUT TAKING THIS POSITION? - NOT SINCE THE FORMAL ANNOUNCEMENT HAS OCCURRED. MPS BOARD PRESIDENT MICHAEL BONDS SAYS REPLACING THORNTON WON'T BE EASY. DR. MICHAEL BONDS - I DON'T THINK THAT WE'RE GOING TO FIND SOMEONE WITH THE COMMITMENT AND THE COMPASSION FOR KIDS THAT DR. THORNTON HAD. MAYOR TOM BARRETT PRAISED THORNTON FOR TURNING AROUND DISTRICT FINANCES, BUT CALLED THE SEARCH FOR A NEW SUPERINTENDENT AN OPPORTUNITY FOR MPS. MAYOR TOM BARRETT - IT HAS BEEN PAINFUL BUT THEY HAVE ADDRESSED A LOT OF THE FISCAL ISSUES - I THINK THE BIG ISSUES REMAIN THE ACADEMIC ISSUES. WE WANT TO SEE A SIGNIFICANTLY HIGHER GRADUATION RATE. WE WANT TO SEE BETTER PERFORMANCE. GOVERNOR SCOTT WALKER MEANWHILE CHALLENGED MPS TO USE THIS AS A TIME CHANGE ITS OPERATION. GOV SCOTT WALKER - MY HOPE IS THAT AS PART OF THIS PROCESS, THEY'LL NOT ONLY BE LOOKING TO FIND A NEW LEADER, THEY'LL BE LOOKING TO NEW WAYS TO EMBRACE THE TOOLS WE'VE GIVING TO PLENTY OF OTHER SCHOOL DISTRICTS ACROSS THE STATE AND USE THOSE IN MILWAUKEE. AND THERE IS AN INTERESTING TWIST TONIGHT -- THE MILWAUKEE SCHOOL

Israeli Prime Minister Benjamin Netanyahu warned Tuesday that a proposed agreement between world powers and Iran was "a bad deal" that would not stop Tehran from getting nuclear weapons -- but would rather pave its way to getting lots of them and lea...